Biomass harvesters are used to harvest non-grain crop material, i.e., biomass. One type of biomass which has a highly useful energy value is corn cobs. Several important uses for corn cobs include but are not limited to the production of ethanol based fuels, solid fuels, livestock feed, livestock bedding, and industrial absorbents.
A traditional and well known method of harvesting biomass takes the form of a 2 pass operation. In this method, the combine harvester makes the first pass through the field to harvest the grain. As grain harvest takes place, the combine discharges unused plant tissues (biomass) onto the top surface of the field. At a time separate from the grain harvest, a second pass is made through the field to pick up the corn stalks off the top surface of the field and form them into bales, using a tractor and baler apparatus. The tractor is used as a prime mover for the baler apparatus, as shown in U.S. Pat. App. Pub. No. 2008/0271428. Besides the extra time required for a second pass across the field, one problem with a 2 pass system is a portion of the highly valuable corn cobs fall through the teeth of the hay pickup and are lost during process
To address this problem, a more recent 1 pass biomass harvesting method has been developed. The 1 pass method enables a baler or accumulation wagon to be pulled directly behind the grain combine harvester, with the biomass picked up at the rear of the combine by the biomass harvester before it touches the top surface of the ground. Such biomass harvesting systems couple the baler directly with the combine as a prime mover, and use power-take-off (PTO) and/or hydraulic power from the combine's engine to power the baler. There are several issues with the current single pass biomass harvesting method (baling or accumulating), which are presently limiting corn cob production.
With regard to accumulation, harvesting loosely accumulated biomass vs. one-pass corn cob baling requires more labor and materials during the grain harvest. It may also require the combine harvester to slow down or stop, thus negatively impacting the speed of the grain harvest. For example, one present and popular method of loose accumulation is to modify a combine harvester with a blower unit at the rear of the combine below the chopper. The blower accumulates and blasts the loose biomass material into an accumulation wagon. When the accumulation wagon is full, the grain harvester has to stop in order for it to unload. Similar to harvesting a forage product, this requires a separate man in a tractor, with a second accumulation wagon which is used to offload. The second accumulation wagon is then towed away and unloaded. This process requires one extra man and tractor to unload the accumulation wagon. In this example, the essence of the problem is that the extra labor and materials associated with harvesting biomass are required during the grain harvest. This adds complexity and cost to the producer's overall cropping system.
With regard to baling, the present single pass biomass harvesting technology is specific to a particular make or model of combine harvester due to the design of its onboard power plant, chassis, and powertrain. With regard to the powerplant, the combine's engine is used to power the biomass harvester (typically a baler) in addition to the combine during the grain harvest. Due to the size variability and demands of the combine engine's power, this approach makes the biomass harvester's use specific to a single make and/or model and/or age of the combine. For example, a 10 yr. old combine harvester may not have enough extra engine power to operate a one-pass biomass harvester baler, since this was not part of the older combine's original design intent. Thus, in order for a producer to harvest biomass in the form of bales with the current single pass method, it would be necessary to purchase a newer combine harvester. Purchasing a newer combine may represent a cost prohibitive risk for many producers; thus, limiting overall biomass production.
With regard to the chassis and powertrain, the present single pass biomass harvesting technology directly connects a biomass harvester (typically a baler) to the combine. Due to the weight of the biomass harvester, the load requirement on a combine's chassis and propulsion system may become excessive. For example, a 10 yr old combine harvester may experience a higher frequency of breakdowns due to the added weight of pulling the biomass harvester, again since this was not part of the older combine's original design intent. It is also specific to a particular make or model of combine harvester due to the strength of it's chassis and drivetrain.
A third issue with the present single pass method is that using a combine harvester to power and pull the biomass harvester can also potentially slow down the grain harvesting process, by added power and load requirements. Specifically, the added power requirements of the biomass harvester may potentially impact the combine's ground speed. The added weight of the biomass harvester may potentially impact the combine's reliability and cause downtime otherwise not experienced when it was used only for grain harvesting. Slowing down the grain harvest in a time when producers demand more productive products and solutions is not an ideal situation.
What is needed in the art is a biomass harvesting system which effectively harvests corn cob biomass, which is discharged from a primary harvester before it contacts the ground, while at the same time does not substantially decrease available horsepower or require excessive towing loads from the primary harvester.